Apparatus for flocculating treatment of liquids in horizontal through-flow tanks



D. a. WILLIAMSON ETAL June 25. 1968 3,389,892

APPARATUS FOR FLOCCULATING TREATMENT OF LIQUIDS IN HORIZONTAL THROUGH-FLOW TANKS 2 Sheets-Sheet. 1

Filed Feb. 13, 1967 INVENTORS. DAVID E. WILLIAMSON BYJIOSEPH 4.

M/mfi INATZ ATTORNEY Julie 1968 o. WILLIAMSON ETAL 3,339,392

APPARATUS FOR FLOCCULATING TREATMENT OF LIQUIDS IN HORIZONTAL THROUGH'FLOW TANKS Filed Feb. 13, 1967 2 Sheets-Sheet 2 INVENTORS. DAVID E. WI L L IAMSON JOSEPH A. R/NATO United States Patent 3,389,892 APPARATUS FOR 'FLOCCULATING TREATMENT OF LIQUIDS IN HORIZONTAL THROUGH-FLOW TANKS David E. Williamson, Norwalk, Conn., and Joseph A.

Rinato, Bronx, N.Y., assignors t0 Dorr-Oliver Incorporated, Stamford, Conn., a corporation of Delaware Filed Feb. 13, 1967, Ser. No. 615,727 16 Claims. (Cl. 259-400) ABSTRACT OF THE DISCLOSURE This invention relates to apparatus for the flocculating treatment of suspensions of solids or of turbidity in liquids in a horizontal through-flow tank by way of gentle mechanical agitation, whereby the suspended solids are rendered as settleable floc structures to be removed from the carrier liquid by subsequent sedimentation-clarification and/ or by filtration.

The liquids or suspensions to be treated in the apparatus of this invention may, for example, comprise raw water, sewage, trade Wastes or any suspension wherein it is desired to flocculate the solids through the operation of a suitable agitating mechanism in a fluocculating tank, with or without the aid of flocculating chemicals.

More particularly, this invention is concerned with improving the agitating mechanism that operates in a horizontal through-flow tank, of the type disclosed in US. patent to Lindell No. 3,164,379. That mechanism comprises horizontally extending flexible agitating means endwise suspended in the manner of a catenary, and means for moving this assembly up and down in the body of liquid in the flocculating tank by moving the ends of the agitating means substantially synchronously along respective predetermined paths.

More particularly,.the mechanism in the reference patent is shown to comprise flexible agitator elements in the form of bands or ribbons endwise suspended in the manner of caternaries suitably spaced late-rally from one another. These agitating elements consist of tough flexible strip material, for example thin gauge stainless steel band which may be between .010 and .020 inch thick and 2 to 4 inches wide. Each end of this bank of agitator elements is supported from the lower end of a depending frame structure through a hinge connection, each frame structure being swingable about a horizontal axis located above the liquid level, the axes of the two frame structures being horizontally spaced from, and parallel to one another. Swinging movement imported to one of these supporting frames is transmitted to the other frame. Both frames thus being motivated substantially in unison will produce up-and-down movement to the bank of agitator elements, thus to impart to the body of liquid the desired type of agitation.

The agitating mechanism thus conceived according to the aforementioned reference patent is simple, inexpensive, and light in weight, and can be readily fabricated substantially from readily available purchasable or readily producible parts. Moreover, by the use of the flexible agitator elements this mechanism can be readily adapted to any size of horizontal through-flow tank. In operation, this agitating mechanism is efiicient in the sense that its agitating effect will reach and pervade substantially all parts of the body of liquid in the tank. Moreover, the supporting frames may be arranged for swinging movement upwardly to a point where the terminals of the ribbons and possibly the ribbons themselves can be inspected above the level of the liquid in the tank.

However, over a long period of time in operation the "ice band material of the agitator elements may become subject to fatigue due mainly to catenary tension stresses combined with the effect of the reversals of flexure of the agitator elements incident to the continuous up-and-down movement of the assembly in the body of liquid in the tank. Such tension stresses will increase with increasing agitating speed-s.

According to one feature of the invention, undue stresses and fatigue effects in the agitating ribbons especially at the ends thereof are eliminated by the provision of relief connections or tension cable means interconnecting the frame structures preferably at the lower ends thereof. These relief cables are shorter than the ribbon elements, and preferably of adjustable length, thus assuring that the agitator bands will assume a substantially predetermined catenary shape of sufficient slackness to avoid excessive catenary tension stresses at the terminals of these agitator elements.

In a practical and novel combination of elements according to the invention, the motivating force is applied to the first frame structure through draft cable means cooperating with the relief cable means for transmitting the movement from one frame structure to the other. One end of the draft cable means is connected to the lower end portion of the one frame structure, and the other end connected to a reversible winding means mounted atop the flocculating tank, or to any means whereby the draft cable means can be drawn in and paid out alternatingly to effect substantially synchronous and substantially stress-free movement of the frames. In this way, minimum actuating stresses are imposed upon any of the operating parts of the mechanism, while the extent and speed of movement of the assembly is readily control lable.

This invention furthermore provides novel terminals connecting the agitator elements to the respective supporting frames, specially constructed to resist fatigue stresses and wear and tear. The improved terminal of the flexible agitator elements is in the form of a simple loop or sling of slender configuration, preferably formed by the strip material itself, the loop being of a length significantly greater than its greatest width. The inner face of this loop may have fixed or bonded thereto a bearing liner of flexible long-wearing tough material, for example Teflon or the like, suitable for underwater operation. Each of the depending supportin frames includes a lower transverse rod or member interconnecting the sides of the frame, which rods extend through the respective rows of terminal loops of the assembly or bank of agitator elements. The slender shape of the loops in combination with the bearing liner material and with the stress-relieving cables render the end portions of the agitator elements highly resistant to the above-mentioned fatigue effects in spite of the reversals of flexure in the operation.

Specific features lie in the construction of the swinging frames, in the manner of connecting the various cable elements with the frames, as well as in the specific const-ruction of the loops and in the manner of preparing them, and in the provision of spacer means for interconnecting the looped ends of the agitator elements. As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within the metes and bound-s of the claims, or of forms that are their functional as well as conjointly cooperative equivalents, are therefore intended to be embraced by those claims.

FIG. 1 is a plan view of the flocc-ulating apparatus of this invention, with the swingable support frames interconnected by the catenaiy-shaped agitator bands as well as by the relief cables, the assembly being actuated by a draft cable device.

FIG. 2 is a longitudinal vertical sectional view taken on line 22 in FIG. 1, illustrating the effect of the stress-relief cables on the catenary shape of the flocculating elements or bands.

IG. 3 shows details of the flocculating apparatus taken from FIG. 2, especially of the terminal loops of the agitator bands, and of the various cables.

FIG. 4 is a plan view taken on line 4-4 in FIG. 3.

In the example herein illustrated, the flocculating apparatus is installed in a horizontal throughflow treatment tank of rectangular elongate shape having a flat bottom 11, side walls 12 and 13, an influent end 14, and an cffluent end 15.

The flocculating apparatus comprises a bank of parallel flexible agitator elements or bands 16 having loopshaped terminals 17 and 18 respectively connected to the lower ends of respective swingable support frames 19 and 20. The support frames depending into the liquid body in the tank are swingable about parallel axes extending transversely of the tank. Each frame itself is a rigid structure swingable in a pair of bearings 21 and 22 mounted upon respective side walls of the tank.

The swingable frames may have transverse bars or slats 23 providing rigidity for the frames, as well as agitation.

The actuating means for raising or lowering this assembly comprise a pair of draft cables 24 and 25 having their lower ends attached to the lower ends of respective sides of the swingable support frame 20.. The upper ends of these draft cables are attached to respective winding drums 26 and 27 fixed upon a shaft 28 rotatable in a pair of bearings 29 and 38. A reversible motor 31 will wind up the draft cables when driving the shaft in the one direction, and will unwind these cables when driving the shaft in the opposite direction, thus imparting up-anddown reciprocating movement to the assembly of agitator elements.

The length of each of the draft cables is adjustable by means of a turnbuckle 24a. The lower end of each of these cables has a terminal loop 24b turn-able on a pin 24c through a shaped member 24d surrounded by the loop. The pin is mounted in a bracket 24a fixed to the end face 54 of frame 20.

More particularly (see aiso FIGS. 3 and 4), each swingable frame mainly comprises a transverse tubular top end member or shaft 32 supported in the bearings, a pair of side members 33 and 34, and a transverse bottom end member in the form of a tubular element 35 interconnecting the lower ends of the side members 33 and 34.

The lower transverse tubular member 35 of each frame is surrounded by the respective loopshaped terminals of the agitator bands, and is detachably connected to the side member. That is, each end of member 35 is fastened to a terminal plate 36 of a respective side member by means of a U-shaped clamp 37 tightened by a pair of nuts 38 and 39.

From FIGS. 3 and 4, it will be further seen that the side members 33 and 34 are hollow and of box-shaped rectangular cross-sectional configuration, closed at the lower end by the bottom terminal plate and at the upper end by a portion 36a rigidly connected to the transverse tubular top end member 32 (see FIG. 2).

More specifically and preferably, each of the agitator elements in this example consists of a flexible band of stainless steel of very small thickness as compared to its width, for instance 0.010 to 0.020 inch thick and perhaps 2 to 4 inches wide. Each end of this band is bent upon itself to constitute a loop securely closed for instance by means of rivets 40. These terminal loops surrounding the respective lower tubular members of the frames, are of a slender tapering configuration, significantly longer 4 than their greatest width determined by the diameter of the tubular transverse members 35.

These terminal loops since they must be swingable about the members 35, are provided with an under-water or water-lubricated bearing liner or layer 40a of flexible tough-wearing material, for instance a strip of flexible composition material such as Teflon or the like which may be bonded to the inner face of the loop. This bearing liner or Teflon strip material may be of the same Width as the stainless steel agitator band, and be of similar thickness, that is in the order of 0.01 inch.

In the process of preparing these terminal loops 17 and 18, a suitable length of the stainless steel strip material or band is cut from a supply or reel of such material. To each of their straight and fiat end portions of this steel band is then flatwise applied a length of the lining or hearing strip material, preferably at least sufiiciently long to provide the lining shown in FIG. 3. The two materials are bonded flatwise to each other by means of a suitable bonding substance or by a bonding operation, whereby the bond remains flexible after it has taken hold. A strip of lining material may be used with one side prepared to be self-adhering.

However, a bearing liner or layer of bearing material may also be applied for instance as a suitable coating applied to the prepared end portions of the steel strip, for instance by dipping or otherwise. For this purpose, the coating material may be a material that is initially sufficiently fluid or viscous and self-adhering, but will remain relatively flexible.

The end portions of the bands thus prepared are then formed into loops substantially as shown in FIG. 3, and securely closed, for instance by means of the rivets 40, so that a double layer of the liner material is confined and compressed within the closure end portion of the loop. Matching rivet holes may be drilled either before or after the loop is formed. In the example of FIG. 3 the length of the closure end portion of the loop is indicated by the length L1, while the loop shape itself is indicated by the length L-Z.

It will be seen that the thus prepared terminal loops of the agitator bands may he slid over the respective detached tubular members 35', whereupon these members are fastened to the respective side members of the respective frames by the U-shaped clamps 37 in the manner above described.

In a preferred embodiment the agitator bands about 2 to 4 inches wide may be spaced apart about 6 to 12 inches from the center line to center line. This spacing is secured by a spacer bar 41 clamped to the closure end of the loops by means of clam-p members or clips 42 and bolts 41a, thus serving additionally to secure the closure of the loops.

Other transverse spacer elements 42a (see FIG. 1) are fastened to the agitator bands at intervals to keep the agitating faces of the bands properly aligned. These spacer elements may be in the form of bars, or they may consist of a strip material similar to that of the agitator bands themselves. If provided in sufficient number parallel to one another, these transverse elements may also present agitating faces in addition to those of the agitator bands themselves.

It is to be noted that, according to this invention, cat naiy tension stress at the ends of the agitator bands may be effectively absorbed by the slender shape of the loops which loops also effectively counteract potential bending stresses which may occur due to recurrent deflections of the agitator bands incident to the up-and-down reciprocating movement of the assembly.

However, the catenary tension stress in the terminals, while dependent upon the speed of movement of th agitator elements through the water, is limited or minimized by the provision, according to this invention, of a pair of relief cables 43 and 44 interconnecting respective side members of res pcctive frames.

These relief cables being of an adjustable length and shorter than the agitator bands transmit the actuating force from frame to frame 19, thereby permitting the agitator bands to assume a substantially pre-determined catenary shape of stress-favorable configuration.

In this way, the relief cables assume the burden of lifting frame 19 when frame 20 is actuated by the draft cable winding device, while only the remaining limited catenary tension need be absorbed by the above described Teflon-lined loops of the agitator bands. Moreover, actuating force is efficiently applied by the draft cables to the lower end portion of frame 20 adjacent to anchoring brackets of the relief cables, thereby minimizing the stresses in the draft cables as well as in the associated frame, and minimizing the actuating power requirement.

Each of the relief cables has loop-shaped terminals 24b swingably connected to respective anchoring brackets 47 and 48 fixed to respective inner faces 49 and 50 of respective side members of the frames. Each of the cable loops 24b is swingable about a pin 51 surrounded by a shaped member 52 hugged by the loop. The effective length of each of the relief cables is adjustable for instance by means of a turnbuckle 53 relative to the catenary length of the agitator bands. Each pin 51 is held and secured in the respective brackets 47 and 48.

From the details of FIGS. 3 and 4 it is also noted that the actuating draft cables are fastened to respective end faces 54 of the side members of frame 20, in such a manthat the outer side faces 55 and 56 of these members are unencumbered and may be located in close proximity to the side walls of the tank as indicated by distance d. For practical reasons, the distance of the fastening of the draft cable from the terminal plate 36 is indicated by the distance D1, while the additional distance of the fastening of the relief cable is indicated by the additional distance D2.

It will be understood that each of the elements or two or more together, of the apparatus herein described, may also find useful application in agitator mechanisms other than the type described above.

Furthermore, while the invention has been illustrated and described as embodied in an agitating mechanism comprising an assembly of agitator bands having terminal loops, relief cable means, and a draft cable winding device, it is not intended to be limited to the details shown, since various modifications and structural as well as functional changes may be made without departing from the spirit of the present invention.

We claim:

1. In a horizontal throughfiow type of liquid treatment tank, an agitating apparatus which comprises a first frame structure mounted for swinging movement about a horizontal axis and extending from said axis into the liquid body in said tank, and having a lower transverse member spaced a substantial distance from said horizontal axis parallel thereto;

a second frame structure mounted for swinging movement about a horizontal axis parallel to, and horizontally spaced a substantial distance from said first horizontal axis, and extending from its axis into the liquid body in said tank, and having a lower transverse member spaced a substantial distance from said horizontal axis parallel thereto;

a bank of substantially horizontal agitator elements of band-shaped configuration consisting of a flexible and relatively thin and tough strip material of a width presenting substantial horizontal agitating faces;

hinge means for connecting the ends of said agitator elements to respective lower transverse members of said frame structures, whereby said agitator elements are suspended in catenary fashion from said frame structures;

flexible tension means interconnecting said frame structures in such a manner as to maintain slackness of the catenary shape of said flexible agitator elements when movement is transmitted through said flexible tension means from the one to the other frame structure,

and actuating means for imparting said swinging movement to said one frame structure, thereby imparting up-and-down movement to said agitating elements in said body of liquid in the tank.

2. The apparatus according to claim 1, wherein adjusting means are provided for increasing or decreasing the effective length of said flexible tension means, and thereby varying the degree of slackness of said agitator elements.

3. The apparatus according to claim 1, wherein said flexible tension means comprise a pair of substantially horizontal and substantially parallel flexible linear elements horizontally spaced spaced from one another.

4. The apparatus according to claim 1, wherein said drive means comprise reversible winding means mounted a horizontal distance away from the axis of said one frame structure, and flexible draft means having one end connected to said frame structure at least a substantial distance away from said axis, and the other end connected to said winding means, said winding means being effective through said draft means and said flexible tension means to raise said agitator elements when said winding means is rotated in one direction, and to lower said agitator elements when rotating said winding means in the opposite direction, whereby the lifting force from said draft means is transmitted through the lower portion of said frame structure to said tension means while maintaining said slackness of the catenary shape of the agitator elements.

5. The apparatus according to claim 1, wherein said lower transverse member of the frame structure is a cylindrical member, and said hinge means comprise a slender loop formed by the end portions of said agitator elements and flatwise slung around respective cylindrical members, said loop being of a length significantly greater than its greatest width.

6. The apparatus according to claim 1, wherein said lower transverse member of the frame structure is a cylindrical member, and said agitator elements consist of stainless steel band material, and wherein said hinge means comprise a slender loop of tough band material and flatwise slung around respective cylindrical members, said loop being of a length significantly greater than its greatest width.

7. The apparatus according to claim 1, wherein said lower transverse member of the frame structures is a cylindrical member, and said agitator elements consist of stainless steel band material, and wherein said hinge means comprise a slender loop formed by the end portions of said agitator elements and slung around respective cylindrical members, said loop being of a length significantly greater than its greatest width, and a layer of tough flexible underwater bearing liner material is fixed to the inner face of said loop.

8. In a horizontal throughflow type of liquid treatment tank, an agitating apparatus which comprises a first frame structure mounted for swinging movement about a horizontal axis and extending from said axis into the liquid body in said tank, said frame structure comprising a pair of side members each having a transverse terminal plate fixed to its lower end, and a lower transverse cylindrical member firmly held against the respective bottom faces of said plates in a position such that the transverse member extends substan ially in the plane defined by the longitudinal axis of said side members of the frame structure;

a second frame structure substantially similar to said first frame structure, mounted for swinging movement about a horizontal axis parallel to, and horizontally spaced a substantial distance from said first horizontal axis, and extending from its axis into the liquid body in said tank;

a bank of substantially horizontal flexible agitator elements of thin stainless steel band material of a width presenting substantial horizontal agitating faces;

hinge means for connecting the ends of said agitator elements to the respective lower transverse members of said frame structures, whereby said agitator elements are suspended in catenary fashion from said frame structures, said hinging means comprising a slender loop formed by the end portions of said agitator elements and flatwise slung around respective lower transverse members of said frame structures, said loop being of a length significantly greater than its width, and a layer of tough flexible underwater bearing liner material fixed to the inner face of said loop;

flexible tension means interconnecting said frame structures in such a manner as to insure slackness of said flexible agitator elements when swinging movement is transmitted through said flexible means from the one to the other frame structure, said tension means comprising a pair of substantially horizontal and substantially parallel flexible linear tension elements horizontally spaced from one another, and connected to respective side members of the frame structures adjacent to the lower ends thereof, and adjusting means for increasing or decreasing the effective length of said linear tension elements;

and actuating means for producing swinging movement to said one frame structure, thereby imparting up-and-down movement to said bank of agitating elements in said body of liquid in the tank.

9. The apparatus according to claim 8, wherein said tension elements have terminal hinge connections with said side members, disposed at the respective inner sides thereof.

10. In a horizontal throughflow type of liquid treatment tank, an agitating apparatus which comprises a first frame structure mounted for movement about a horizontal axis and extending from said axis into the liquid body in said tank;

a second frame structure mounted for movement about a horizontal axis parallel to, and spaced a substantial horizontal distance from said first axis, said frame structure extending from said axis into the liquid body in said tank, and having a transverse member spaced a substantial distance from said horizontal axis;

flexible agitating means endwise hingedly connected in catenary fashion to respective transverse members of said frame structures;

flexible tension means interconnecting said frame structures in such a manner as to maintain slackness of the catenary shape of said flexible agitating means when oscillating movement is imparted to one of said frame structures, and such movement is transmitted through said flexible tension means to the other frame structure;

and means for imparting said oscillating movement to said one frame structure, thereby imparting up-anddown movement to said agitating means in said body of liquid in the tank.

11. In a horizontal throughflow type of liquid treatment tank, an agitating apparatus which comprises a first frame structure mounted for swinging movement about a horizontal axisand extending from said axis into the liquid body in said tank, and having a lower transverse cylindrical member spaced a substantial distance from said horizontal axis parallel thereto;

a second frame structure mounted for swinging movement about a horizontal axis parallel thereto, and horizontally spaced a substantial distance from said first horizontal axis and extending from its axis into the liquid body in the tank, and having a lower transverse cylindrical member spaced a substaniial distancefrom said axis parallel thereto;

a bank of substantially horizontal agitator elements in the form of thin flexible band of tough material of high tensile strength and of a width presenting substantially horizontal agitating faces;

hinge means for connecting the ends of said agitator elements to respective lower transverse members of said frame structures, whereby said agitation elements are suspended in catenary fashion from said frame structures, said hinge means comprising a slender loop of tough band material provided at each end of the agitator elements, and flatwise slung around respective lower members of said frame structures, said loop being of a length significantly greater than its width; and actuating means for producing swinging movement to said frame structures, thereby imparting up-and-down movement to said bank of agitating elements in said body of liquid in the tank.

12. The apparatus according to claim 11, wherein said loop comprises a band of tough flexible underwater bearing material.

13. The apparatus according to claim 11, wherein said band material is of stainless steel, and said loops consist of the respective end portions of the band material of said agitator elements, with a layer of tough flexible underwater bearing material fixed to the inner face of said loop.

14. The apparatus according to claim 11, with the addition of a spacer bar extending transversely of the agitator elements adjacent to the looped ends thereof, and means for clamping each agitator element to said spacer bar.

15. The apparatus according to claim 1, wherein said lower transverse member of the frame structure is a cylindrical member, and wherein said hinge means comprise slender loops in the form of tough'band material slung around respective transverse cylindrical members of the frame structures, said loops being of a length significantly greater than its greatest Width, said loop-s comprising respective end portions of the strip material of the agitator elements.

16. The apparatus according to claim 1, wherein said lower transverse member of the frame structures is a cylindrical member, and wherein said hinge means comprise slender loops in the form of a band of tough flexible underwater bearing material slung around respective cylindrical members, said loops being of a length significantly greater than its greatest width.

References Cited UNITED STATES PATENTS 3,164,379 1/1965 Lindell 259-400 3,279,764 10/1966 Gibbs 25999 ROBERT W. JENKINS, Primary Examiner. 

